Option A. Most other high-end word processors (Word Perfect, for example) are capable of converting .doc files if they are first saved on your PC disk. In MS Explorer, first right-click on the link to the desired document, choose the "Save Target As.." option, and provide filename and destination in the resulting window. In Netscape, you can still left-click on the link and then just choose the "Save to Disk" option (rather than "Open It") which will then ask for filename and destination. Then start up your local word processor, and use that to open the saved file. 

Option B. Microsoft provides free downloads of Viewer software for Windows systems that can be set to automatically open .doc files for onscreen reading and for printing -- but without any editing capability. (Installation on a system which DOES already have functioning MS Word is not advised for casual users, as it might potentially conflict with Word's default connections to browsers, printers, etc.) 
This takes some time and effort -- perhaps 15-20min, depending on connection speed -- to download and install. The advantage of this option is that this download only has to be performed once. Then future .doc files, whether in browser window or as email attachments, will open automatically in the viewer window. Go to the download section on the main microsoft.com website (http://www.microsoft.com/downloads/), find the latest version of "Word Viewer" (either search for that phrase, or explore the "Office and Home Applications" button on the left menu), and follow instructions to download and install.

Hint to navigate .doc files online...

Both Word itself and the free Viewer described above have a display option that may help find one's way in long documents. First, see whether the document opens in a single frame, or with a separate panel along the left edge. If the left panel does not appear, go to the "View" pulldown menu on the top bar and select "Document Map".

When this left panel is open, it shows the structure of any header levels that appear inside the document. Clicking on any of these section titles will take the document view in the right panel directly to that section. Unfortunately, this only works for documents that were originally constructed using Header tags. If nothing appears in the left panel, then scrolling is the only option.